Republic Aviation F-105 was a supersonic fighter-bomber capable of Mach-2 speeds The Republic Aviation F-105 was a supersonic fighter-bomber capable of Mach-2 speeds. The aircraft was initially an internal Republic project designed to replace the RF-84F Thunderflash. The U.S. Air Force awarded Republic with a contract for 199 aircraft in September of 1952, but later downgraded the order in size. Near the end of 1953, the entire program was canceled by the Air Force due to a number of delays and uncertainties regarding the aircraft. In 1954, it placed another order, and the YF-105A prototype first flew in October of 1955. The first production F-105B was accepted by the Air Force in May of 1957. In June 1957 Republic Aviation requested that the F-105 be named Thunderchief, continuing the sequence of the company’s Thunder-named aircraft, e.g. P-47 Thunderbolt, F-84 Thunderjet, and F-84F Thunderstreak. F-105 Wild Weasel versions were also built. The F-105 was the largest single-seat, single-engine combat aircraft in history, weighing in at about 50,000 pounds. The Mach-2 capable F-105 conducted most of the strike bombing missions during the early years of the Viet Nam War. Over 20,000 Thunderchief sorties were flown during the war, with 382 F-105 aircraft lost. One of its nicknames was “Thud”. F-105 Thunderchief of the USAF ThunderbirdsF-105 Thunderchief of the USAF Thunderbirds Six airshows by the USAF Thunderbirds demonstration team were flown in 1964 using the F-105. Following an in the F-105, the Thunderbirds transitioned back to the F-100 Super Sabre.